1. Field of the Invention
The present invention generally relates to a liquid crystal display device, and more particularly relates to a liquid crystal display device manufactured by one drop fill (ODF) process and a method for manufacturing the same.
2. Description of the Related Art
Generally, conventional liquid crystal display (LCD) devices include a light source and a LCD cell and control the transmission of light by utilizing the birefringence characteristic of liquid crystal thereby displaying variety of images. In a process of making LCD panels, two substrates are generally assembled together as a cell by a sealing material with only an injection hole left thereof, and then a liquid crystal material is injected into the cell gap formed between the two substrates. Finally, the injection hole of the cell is sealed.
There has been a new technique recently provided in which a liquid crystal material is dispensed upon a substrate and the other substrate is covered thereupon. This technique greatly reduces the steps of a process of making LCD panels and improves manufacturing efficiencies. More specifically, the one drop fill (ODF) method includes the following steps. First, a sealant is applied to the whole periphery of one of a pair of substrates so as to form a sealing member and then a liquid crystal material is dispensed upon one of the pair of substrates. After the dispensing step, one substrate is superposed upon the other one and then the sealing member is to be cured. It should be noted that, in this method, a pure thermosetting sealant can not be used in the step of dispensing the liquid crystal material before the two substrates are sealed. Accordingly, the sealant for forming the sealing member is preferably a radiation-curable adhesive (e.g. an ultraviolet-curable adhesive).
Compared to the vacuum injection method widely utilized in making LCD cells, the one drop fill (ODF) method can greatly reduce the manufacturing cost of LCD cells and improve the yield rate due to following reasons. First, the ODF method can reduce the usage amount of liquid crystal material. Secondly, it can also reduce the time for liquid crystal material injection. Therefore, there exists a strong necessity of applying the ODF method to the process of manufacturing LCD cells.
However, in the ODF method, the sealing member formed before the liquid crystal material being dispensed is required to fully enclose a display region of one substrate without leaving any opening thereof. When the sealing member is formed by an application manner, it is designed to have an overlapping segment between the initial end and the final end of the sealant so as to ensure that the formed sealing member can fully enclose the display region. However, the usage amount of the sealant for forming this overlapping segment is generally more than that for forming other parts. Besides, at the beginning of applying the sealant, the applied amount of the sealant is not easily controlled resulting in that the applied amount of the initial end being too large. Therefore, after dispensing the liquid crystal material and superposing the two substrates, the shape of the initial end of the sealant is usually larger than its predetermined size and thus overlapped by a light-shielding matrix of the substrate. Consequently, in the step of curing the sealing member by a radiation (e.g. ultraviolet), the part of the sealant covered (overlapped) by the light-shielding matrix will not be completely cured due to not obtaining rays from the radiation. Further, the uncured part of the sealant will react with the liquid crystal material and thus adversely affect the performance of the liquid crystal material.
Accordingly, in order to ensure that the sealing member can be completely cured so as not to react with the liquid crystal material, the distance between the sealing member and the part of the light-shielding matrix that causes a light-blocking effect should be kept larger. It signifies that the area outside the display region of an LCD panel should be increased or that the area of the display region should be reduced in an LCD panel having a fixed size. However, these significations are apparently not the trend of developing liquid crystal displays.
Accordingly, the present invention provides a liquid crystal display that can overcome or at least improve the above-mentioned problem situations.